Figure 8
From: Dual frequency sound absorption with an array of shunt loudspeakers

(a) Measurement apparatus for normal absorption coefficients, (b) the position of the microphones and the sound sources in the reverberation room, (c, d) the photo of the measurement setup without (c) and with (d) the shunt loudspeaker array in the reverberation room [drawn with Adobe Illustrator CC 2018 (https://itsc.nju.edu.cn/adobe/list.htm)].